The U.S. Food and Drug Administration advisers on Thursday backed the use of Sanofi (SASY.PA) and partner AstraZeneca's (AZN.L) experimental antibody to prevent respiratory syncytial virus (RSV) infections in infants.
The advisers voted unanimously in favor of using the antibody, nirsevimab, in newborns and infants to prevent infections in their first RSV season.
In a separate 19-2 vote, the panel backed the therapy's use in children aged up to two years who are vulnerable to severe illness through their second RSV season.
Swedish Orphan Biovitrum's (SOBIV.ST) treatment Synagis is currently the only approved preventive therapy in the United States for infants against RSV, a leading cause of pneumonia in toddlers and the elderly.
Unlike Synagis, which is approved for high-risk infants and has to be given as monthly injections, Sanofi-AstraZeneca's nirsevimab is a long-acting therapy expected to be given once every season to prevent the RSV infection regardless of additional medical conditions in infants.
"This is probably the closest thing to an RSV vaccine that we have and it really moves the field forward," said Nimish Patel, a panel member and professor at the University of California San Diego.
A majority of hospitalizations due to RSV happen during the infants' first year of life, but certain chronic lung and heart conditions increase the risk of severe infections during their second year, according to American Academy of Pediatrics.
The FDA, which is not obligated to follow the recommendations of the advisory panel but usually does, is expected to make a decision on the therapy by the third quarter of this year.
Two studies showed the therapy was effective in preventing lower respiratory tract infections, the FDA staff reviewers had said on Tuesday, but added that benefits and risks for babies older than eight months may need additional consideration.
Nirsevimab's peak sales are estimated to touch $2 billion, according to Morningstar analyst Damien Conover.
